They have been skating __________.
#40389
A
for three hours
B
since three hours ago
C
three hours ago
D
since three hours
推荐题目
His English ________ a lot since he took the course.
#37514
A
improved
B
was improved
C
has improved
D
has been improved
There ________ elephants if we don’t protect them now.
#40105
A
will have no
B
won’t be any
C
won’t be some
D
will be some
We __________ sightseeing tomorrow.
#38659
A
go
B
goes
C
are going
D
is going